1. Field of the Invention
The present invention relates to an oval speaker apparatus employing a diaphragm and a voice coil whose outer peripheral shapes in a plan view are oval or elliptical, as well as a method of manufacturing the same.
2. Description of the Related Art
Generally, an electrodynamic speaker has a round diaphragm, a round voice coil for driving this diaphragm, an edge joined to an outer periphery of the diaphragm, a frame to which an outer peripheral edge of this edge is fixed, a magnetic circuit on the frame for housing the voice coil, and lead wires led out from the voice coil.
Further, a wiring structure is configured that the lead wires led out from the voice coil are wired in such a manner as to traverse the diaphragm and the edge in the radial direction, extend along surface of the diaphragm or the edge, and are led out from the outer peripheral edge of the edge.
In such a wiring structure of the lead wires, if a wiring is configured straightly over the surface of the diaphragm or the edge, abnormal noise such as buzzing is generated due to amplitude of the diaphragm and the edge during operation. In addition, bending load or tensile load comes to be repeatedly applied to the lead wires, possibly resulting in the disconnection of the lead wires. Accordingly, methods of manufacturing a speaker in which a wiring is configured by providing slack have been proposed (refer to JP-A-8-223687, for example).
Meanwhile, as one of electrodynamic speakers, attention has recently focused on an oval speaker apparatus employing a diaphragm whose outer peripheral shape in a plan view is oval or elliptical.
Since the outer peripheral shape of the diaphragm in a plan view is oval or elliptical, as compared with a general speaker apparatus using the round diaphragm, this oval speaker apparatus has advantages in that not only can it be easily mounted in such as a space where a width is narrow, but it is possible to obtain a wide area on the diaphragm by portions expanding in its major-axis direction, making it possible to improve the low-range reproduction. In addition, in a case where the diaphragm is a dome type diaphragm in which its center protrudes from its peripheral edge, as compared with a cone type in which its center is concaved to the inner recess, there is no containment of high-frequency components, and a radiation angle of sound is wide. Therefore, there are also advantages that the directionality is weak, and degree of freedom of mounting in an apparatus or the like improves.
Namely, the oval speaker apparatus is very useful as a high-performance micro speaker which is mounted in a portable telephone or portable audio equipment, and studies have been made devotedly.
In such an oval speaker apparatus as well, to prevent amplitude of the edge from resulting in generating the abnormal noise such as buzzing and the disconnection of the lead wires, it is also effective to wire the lead wires by providing slack, as described above.